1. PH 105 Dr. Cecilia Vogel Lecture 16

2. OUTLINE  envelope  resonances  plate  air  tunings  guitar

3. Envelope of Plucked String  The envelope of a plucked string  has a rapid ____  and a longer _____  no _________  the harmonic content of the decay becomes ______ with time.

4. Envelope of bowed String  The envelope of a bowed note  has a less rapid ______  and a quick _______  Sustain lasts as long as bowing continues  sustain has fairly _________  the ______ is similar to decay of plucked string.

5. String Sound  The sound of stringed instrument  is due to three factors:  the source of the sound  resonators  the method of radiating  1) the source of the sound  determines  the strings: alone very quiet  produce all harmonics if  many if

6. String Sound  2) resonators  bridge, front and back plates   volume of air   video -- why need washtub?  3) the method of radiating  directly (front plate only)  through sound hole or f-holes

7. Body Resonances  Guitar often has ______________  at about 102, 193, 204 Hz  many higher resonances  If a string harmonic matches a resonant freq  it will be

8. Resonances and Timbre  Resonances  make  This changes the  which changes the  Tuning the ________  affects the  not just the strings are tuned!

9. Resonances and Timbre  Examples:  strong _____ resonances in violin  2-3 kHz  enhance  10-15 th harmonic of G 3  give ______ quality  strong ____ resonances in guitar  100-400 HZ  enhance the  fundamental and 2 nd harmonic of G 3 196  gives a _____ quality

10. Guitar Strings  E 2, A 2, D 3, G 3, B 3, E 4  (12 string has 6 pairs,  each tuned a _____ higher than previous,  except E:B, which is a ____  fourth is about : ____ ratio, __ semitones  major third is about: ____ ratio, __ semitones  (4/3)(4/3)(4/3)(4/3)(5/4) = almost ___  4(500 ¢)+400¢ =2400¢ = ______

11. Guitar Strings  E 2, A 2, D 3, G 3, B 3, E 4  Can you play F 2 on E-string?  ______ higher  making the string shorter by factor of 1.05946  Frets placed about 1/18 distance from the previous fret (or nut) to bridge  fig 10.39

12. Frets  rule of frets:  place fret at 1/18 th of  length ratio is 18/17 =1.0588, about 99c instead of 100 c  almost a  (1/17.817 more accurate than 1/18)  measure length of string, distance between frets  ratio = ?  Why are other frets closer?

13. Timbre Demo  A-string  Expect strong  110 &220 near resonances (fig 10.31)  play C3 (131 Hz): 1 st harm ___, 2 nd ___  G-string  Expect strong fundamental and 2 nd harm?  196 Hz and 392 Hz near resonances at 200 & 400 Hz ( folk only )  B-string  f1= 246.94 Hz, ___ and ___ harmonics  near 250 Hz and 550 Hz resonance of classical

14. Summary  Vibrations of string,  fundamental and harmonics,  drive resonances in  bridge, plates, air cavity.  Sound quality of different string instruments due largely to tuning resonances.  rule of 18